| Yegorovite | |
| Category: | Silicate mineral |
| Formula: | Na4[Si<sub>4</sub>O<sub>8</sub>(OH)<sub>4</sub>]·7H2O |
| Imasymbol: | Yeg |
| Strunz: | 09.DX.00 |
| Dana: | 65.01.09.01 |
| Symmetry: | P22/c |
| Unit Cell: | a = 9.866(7) Å, b = 12.385(5) Å, c = 14.921(1) Å, β = 104.79(6)°, V = 1762(3)ų |
| Color: | colorless |
| System: | Monoclinic |
| Class: | Prismatic H–M symbol: (2/m) |
| Twinning: | Polysynthetic |
| Cleavage: | perfect on |
| Fracture: | splintery |
| Mohs: | 2 |
| Luster: | Vitreous |
| Streak: | white |
| Diaphaneity: | Opaque |
| Gravity: | 1.90 |
| Density: | 1.90(2) g/cm³ |
| Opticalprop: | biaxial (−) |
| Birefringence: | δ = 0.008 |
| References: | [1] [2] |
Yegorovite, ([Na<sub>4</sub>[Si<sub>4</sub>O<sub>8</sub>(OH)<sub>4</sub>]·7H2O]) is a silicate mineral found in a hyperalkalinepegmatite in the Lovozero Pluton at Mt. Kedykverpakhk in the Kola Peninsula of Russia. It was named in memory of Russian crystallographer Yurii Kavdievich Yegorov-Tismenko, and approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association in 2008.
Yegorovite is colorless, with a white streak. Found in small quantities among pegmatites. It is a natural silicate of alkali cations.
The chemical composition of yegorovite in elemental weight percent is as follows:
| element | weight % | |
|---|---|---|
| Na2O | 23.28 | |
| SiO2 | 45.45 | |
| H2O | 31.27 | |
| Total | 100.0 |
The crystal structure of yegorovite is made up of a single chain of four silicon (Si) tetrahedrons [Si<sub>4</sub>O<sub>8</sub>(OH)<sub>4</sub>]∞ and sixfold polyhedrons of [NaO(OH)<sub>2</sub>(H<sub>2</sub>O)<sub>3</sub>] and [NaO(OH)(H<sub>2</sub>O)<sub>4</sub>] centered by sodium (Na).